Question

The following figure is a ribbon representation of the x-ray crystallographic structure of AnCE, a single domain protein with ACE activity from Drosophila melanogaster, complexed with captopril, (2S)-1-(3-mercapto-2-methylpropanoyl)-L-proline. ACE inhibition kinetics [FAAPGG] Vo, nmol/min uM no inhibitor + captopril + lisinopril + 50-100 KR serum 125 0.95 0.13 0.047 0.42 167 1.05 0.19 0.061 0.53 250 1.54 0.28 0.092 0.65 500 1.9 0.46 0.18 0.91 750 2 0.61 0.26 1.08 a. Use a protein database, such as BRENDA or RCSB, to answer the following questions: 1) what is the E.C. number for this enzyme, 2) what is its classification, 3) what is its reaction product and substrate specificity, and 3) what is its molecular weight? b. What type of secondary structure is predominant? c. What is the length of the longest secondary structural element and how many amino acid residues does it contain?

Answer 1

A. From RCSB:

1. EC number = 3.4.15.1

2. Classification: Hydrolase

3. Reaction product: Angiotensin II

Substrate: Angiotensin I

(AnCE is an angiotensin converting enzyme that converts angiotensin I to angiotensin II.)

4. Molecular weight = 70914 Da or 70.9 kDa.

B. Alpha helix is the predominant secondary structure in this protein.

C. Longest alpha helix region length is 52 Angstrom and it contains 598 amino acids.